text: When the concentration of suspended sediment at the mouth of a river is so large that the density of river water is greater than the density of sea water a particular kind of turbidity current can form called a hyperpycnal plume. The average concentration of suspended sediment for most river water that enters the ocean is much lower than the sediment concentration needed for entry as a hyperpycnal plume.  Although some rivers can often have continuously high sediment load that can create a continuous hyperpycnal plume, such as the Haile River (China), which has an average suspended concentration  of 40.5 kg/m. The sediment concentration needed to produce a hyperpycnal plume in marine water is 35 to 45 kg/m, depending on the water properties within the coastal zone. Most rivers produce hyperpycnal flows only during exceptional events, such as storms, floods, glacier outbursts, dam breaks, and lahar flows.  In fresh water environments, such as lakes, the suspended sediment concentration needed to produce a hyperpycnal plume is quite low (1 kg/m).